Preheat oven to 400°F (200°C). In a microwave-safe bowl combine shredded mozzarella and 3 tablespoons cream cheese. Microwave in 30-second bursts, stirring between bursts, until cheeses are fully melted and smooth (about 60–90 seconds total).

Mix dough

Stir the melted cheese mixture with 1 1/2 cups almond flour, 1 egg, 1 tablespoon granulated sweetener, 1/2 teaspoon baking powder and 1/4 teaspoon salt. Use a spatula initially, then when it cools slightly, knead with clean hands until a uniform dough forms. If dough is too sticky, add up to 1–2 tablespoons more almond flour.

Shape crust

Place dough between two sheets of parchment paper and roll into a roughly 9-10 inch round (or press into a 9-inch round tart pan with removable bottom). Aim for about 1/8–1/4 inch thickness at the edges and slightly thinner in the center. If using a pan, press dough up the sides slightly to create a rim.

Blind bake

Remove top parchment. Dock the crust lightly with a fork. Brush or beat 1 egg with 1 teaspoon heavy cream and brush the crust lightly (this helps set and brown crust). Bake in the preheated 400°F (200°C) oven for 8–10 minutes, until just starting to set and lightly golden. Remove from oven and lower oven temperature to 375°F (190°C).

Bumble Berry Filling

Prepare filling

While the crust bakes, combine 2 cups mixed berries, 1 tablespoon lemon juice, 1 teaspoon lemon zest, 1/2 cup granulated sweetener (adjust to taste), 2 teaspoons arrowroot or tapioca starch and 1/2 teaspoon vanilla extract in a bowl. Toss gently until berries are evenly coated and starch is distributed; this will thicken juices during baking.

Assemble

Once the crust has had its initial bake and oven is lowered to 375°F (190°C), spoon the berry mixture onto the par-baked crust, spreading gently but leaving a small rim if desired.

Top and bake

If you like a lattice or additional dough decoration, reserve a few tablespoons of dough before rolling and form strips to place on top. Brush any exposed dough strips with the egg wash, and sprinkle optional coarse sugar or crushed nuts on top for crunch. Bake at 375°F (190°C) for 18–25 minutes, until berries are bubbling and crust is golden brown.

Finish & Serve

Cool and set

Remove the Bumble Berry from oven and let cool on a wire rack for at least 20–30 minutes so the filling sets and slices cleanly. Cooling also reduces runniness from the berry juices.

Optional garnish

Dust lightly with powdered sweetener or sugar if desired. Serve warm or at room temperature. For keto option, use low-carb sweeteners throughout and omit powdered dusting or use powdered erythritol.